Photographing system, image capturing unit and electronic device

ABSTRACT

A photographing system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element and a seventh lens element with refractive power. The first lens element with positive refractive power has an object-side surface being convex in paraxial region. The second lens element with refractive power has an image-side surface being concave in paraxial region. The third, fourth and fifth lens elements all have refractive powers. The sixth lens element with refractive power has an image-side surface being concave in paraxial region, wherein the image-side surface has at least one convex shape in off-axis region, and both of two surfaces are aspheric. The seventh lens element with refractive power has an object-side surface being concave in paraxial region, and both of two surfaces are aspheric.

RELATED APPLICATIONS

This application is a continuation patent application of U.S.application Ser. No. 14/740,000, filed on Jun. 15, 2015, which claimspriority to Taiwan Application Serial Number 104105620, filed Feb. 17,2015, which is incorporated by reference herein in its entirety.

BACKGROUND Technical Field

The present disclosure relates to a photographing system, an imagecapturing unit and an electronic device, more particularly to aphotographing system and an image capturing unit applicable to anelectronic device.

Description of Related Art

In recent years, with the popularity of electronic devices having camerafunctionalities, the demand of miniaturized optical systems has beenincreasing. The sensor of a conventional optical system is typically aCCD (Charge-Coupled Device) or a CMOS (ComplementaryMetal-Oxide-Semiconductor) sensor. As the advanced semiconductormanufacturing technologies have allowed the pixel size of sensors to bereduced and compact optical systems have gradually evolved toward thefield of higher megapixels, there is an increasing demand for compactoptical systems featuring better image quality.

A conventional optical system employed in a portable electronic productmainly adopts a lens structure with fewer lens elements, such as five orsix lens elements. Due to the popularity of electronic devices withhigh-end specifications, such as smart phones and wearable apparatus,the requirements for high resolution and image quality of presentcompact optical systems increase significantly. However, theconventional optical systems cannot satisfy these requirements of thecompact optical systems.

Other conventional compact optical systems with seven-element lensstructure are developed. However, the conventional compact opticalsystems with seven lens elements are unfavorable for keeping the opticalsystem compact. Therefore, there is an increasing demand to develop anoptical system which satisfies the requirements of high image qualityand compact size simultaneously while having a large aperture and alarge image sensor.

SUMMARY

According to one aspect of the present disclosure, a photographingsystem includes, in order from an object side to an image side, a firstlens element, a second lens element, a third lens element, a fourth lenselement, a fifth lens element, a sixth lens element and a seventh lenselement. The first lens element with positive refractive power has anobject-side surface being convex in a paraxial region thereof. Thesecond lens element with refractive power has an image-side surfacebeing concave in a paraxial region thereof. The third lens element hasrefractive power. The fourth lens element has refractive power. Thefifth lens element has refractive power. The sixth lens element withrefractive power has an image-side surface being concave in a paraxialregion thereof, wherein the image-side surface of the sixth lens elementhas at least one convex shape in an off-axis region thereof, and anobject-side surface and the image-side surface of the sixth lens elementare both aspheric. The seventh lens element with refractive power has anobject-side surface being concave in a paraxial region thereof, whereinthe object-side surface and an image-side surface of the seventh lenselement are both aspheric. The photographing system has a total of sevenlens elements with refractive power. The first lens element, the secondlens element, the third lens element, the fourth lens element, the fifthlens element, the sixth lens element and the seventh lens element areall stationary relative to one another in a paraxial region thereof.There is an air gap in a paraxial region between every two of the firstlens element, the second lens element, the third lens element, thefourth lens element, the fifth lens element, the sixth lens element andthe seventh lens element that are adjacent to each other. When a focallength of the photographing system is f, a curvature radius of theimage-side surface of the sixth lens element is R12, a curvature radiusof the object-side surface of the seventh lens element is R13, thefollowing condition is satisfied:0.30<(f/R12)−(f/R13).

According to another aspect of the present disclosure, an imagecapturing unit includes an image sensor and the aforementionedphotographing system, wherein the image sensor is disposed on the imageside of the photographing system.

According to still another aspect of the present disclosure, anelectronic device includes the aforementioned image capturing unit.

According to yet another aspect of the present disclosure, aphotographing system includes, in order from an object side to an imageside, a first lens element, a second lens element, a third lens element,a fourth lens element, a fifth lens element, a sixth lens element and aseventh lens element. The first lens element with positive refractivepower has an object-side surface being convex in a paraxial regionthereof. The second lens element has negative refractive power. Thethird lens element has refractive power. The fourth lens element hasrefractive power. The fifth lens element has refractive power. The sixthlens element with refractive power has an image-side surface beingconcave in a paraxial region thereof, wherein the image-side surface ofthe sixth lens element has at least one convex shape in an off-axisregion thereof, and an object-side surface and the image-side surface ofthe sixth lens element are both aspheric. The seventh lens element withrefractive power has an object-side surface being concave in a paraxialregion thereof, wherein the object-side surface and an image-sidesurface of the seventh lens element are both aspheric. The photographingsystem has a total of seven lens elements with refractive power. Thefirst lens element, the second lens element, the third lens element, thefourth lens element, the fifth lens element, the sixth lens element andthe seventh lens element are all stationary relative to one another in aparaxial region thereof. There is an air gap in a paraxial regionbetween every two of the first lens element, the second lens element,the third lens element, the fourth lens element, the fifth lens element,the sixth lens element and the seventh lens element that are adjacent toeach other. When a focal length of the photographing system is f, acurvature radius of the image-side surface of the sixth lens element isR12, a curvature radius of the object-side surface of the seventh lenselement is R13, an Abbe number of the first lens element is V1, an Abbenumber of the second lens element is V2, and the following conditionsare satisfied:0.30<(f/R12)−(f/R13); and25<V1−V2<45.

According to yet still another aspect of the present disclosure, animage capturing unit includes an image sensor and the aforementionedphotographing system, wherein the image sensor is disposed on the imageside of the photographing system.

According to yet still another aspect of the present disclosure, anelectronic device includes the aforementioned image capturing unit.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be more fully understood by reading the followingdetailed description of the embodiments, with reference made to theaccompanying drawings as follows:

FIG. 1 is a schematic view of an image capturing unit according to the1st embodiment of the present disclosure;

FIG. 2 shows spherical aberration curves, astigmatic field curves and adistortion curve of the image capturing unit according to the 1stembodiment;

FIG. 3 is a schematic view of an image capturing unit according to the2nd embodiment of the present disclosure;

FIG. 4 shows spherical aberration curves, astigmatic field curves and adistortion curve of the image capturing unit according to the 2ndembodiment;

FIG. 5 is a schematic view of an image capturing unit according to the3rd embodiment of the present disclosure;

FIG. 6 shows spherical aberration curves, astigmatic field curves and adistortion curve of the image capturing unit according to the 3rdembodiment;

FIG. 7 is a schematic view of an image capturing unit according to the4th embodiment of the present disclosure;

FIG. 8 shows spherical aberration curves, astigmatic field curves and adistortion curve of the image capturing unit according to the 4thembodiment;

FIG. 9 is a schematic view of an image capturing unit according to the5th embodiment of the present disclosure;

FIG. 10 shows spherical aberration curves, astigmatic field curves and adistortion curve of the image capturing unit according to the 5thembodiment;

FIG. 11 is a schematic view of an image capturing unit according to the6th embodiment of the present disclosure;

FIG. 12 shows spherical aberration curves, astigmatic field curves and adistortion curve of the image capturing unit according to the 6thembodiment;

FIG. 13 is a schematic view of an image capturing unit according to the7th embodiment of the present disclosure;

FIG. 14 shows spherical aberration curves, astigmatic field curves and adistortion curve of the image capturing unit according to the 7thembodiment;

FIG. 15 a schematic view of an image capturing unit according to the 8thembodiment of the present disclosure;

FIG. 16 shows spherical aberration curves, astigmatic field curves and adistortion curve of the image capturing unit according to the 8thembodiment;

FIG. 17 is a schematic view of a projection of a position of a maximumeffective radius of an image-side surface of a seventh lens element onan optical axis and an intersection of an object-side surface of aseventh lens element and the optical axis in FIG. 5;

FIG. 18 shows an electronic device according to an embodiment;

FIG. 19 shows an electronic device according to another embodiment; and

FIG. 20 shows an electronic device according to still anotherembodiment.

DETAILED DESCRIPTION

A photographing system includes, in order from an object side to animage side, a first lens element, a second lens element, a third lenselement, a fourth lens element, a fifth lens element, a sixth lenselement and a seventh lens element. The photographing system has a totalof seven lens elements with refractive power.

According to the present disclosure, there is an air gap in a paraxialregion arranged between every two of the first lens element, the secondlens element, the third lens element, the fourth lens element, the fifthlens element, the sixth lens element, and the seventh lens element thatare adjacent to each other, that is, each of the first through seventhlens elements of the photographing system is a single and non-cementedlens element. Moreover, the manufacturing process of the cemented lensesis more complex than the non-cemented lenses. In particular, animage-side surface of one lens element and an object-side surface of thefollowing lens element need to have accurate curvature to ensure thesetwo lens elements will be highly cemented. However, during the cementingprocess, those two lens elements might not be highly cemented due todisplacement and it is thereby not favorable for the image quality ofthe photographing system. Therefore, having an air gap in a paraxialregion between every two of the lens elements that are adjacent to eachother in the present disclosure is favorable for avoiding problemsgenerated by the cemented lens elements. Furthermore, the first lenselement, the second lens element, the third lens element, the fourthlens element, the fifth lens element, the sixth lens element and theseventh lens element are all stationary relative to one another in aparaxial region thereof. That is, the aforementioned air gaps are allconstant.

The first lens element with positive refractive power has an object-sidesurface being convex in a paraxial region thereof. Therefore, the firstlens element provides the photographing system with sufficient positiverefractive power. Furthermore, it is favorable for obtaining a propertotal track length of the photographing system.

The second lens element can have negative refractive power. The secondlens element can have an image-side surface being concave in a paraxialregion thereof. Therefore, it is favorable for correcting the aberrationfrom the first lens element so as to improve the image quality.

The third lens element and the fourth lens element both have refractivepower. Therefore, it is favorable for properly distributing therefractive power so as to balance the arrangement of the refractivepowers of the photographing system.

The fifth lens element with refractive power can have an image-sidesurface being convex in a paraxial region thereof. Therefore, it isfavorable for correcting the astigmatism of the photographing system.

The sixth lens element with refractive power has an image-side surfacebeing concave in a paraxial region and at least one convex shape in anoff-axis region thereof. The sixth lens element can have an object-sidesurface being convex in a paraxial region and at least one concave shapein an off-axis region thereof. Therefore, it is favorable for theprincipal point of the photographing system being positioned away fromthe image side of the photographing system so as to reduce a back focaltrack length of the photographing system, thereby keeping a compact sizethereof. Furthermore, it is favorable for effectively reducing theincident angle of the light projecting onto the image sensor andimproving the image-sensing efficiency of the image sensor to furthercorrect the aberration of the off-axis region.

The seventh lens element can have negative refractive power. The seventhlens element has an object-side surface being concave in a paraxialregion thereof. The seventh lens element can have an image-side surfacebeing concave in a paraxial region and at least one convex shape in anoff-axis region thereof. Therefore, the curvatures of the sixth lenselement and the seventh lens element are favorable for an exit pupil ofthe photographing system being positioned towards an image surface ofthe photographing system so as to effectively reduce the back focallength, thereby keeping a compact size thereof. In some embodiments, aprojection P1 of a position of a maximum effective radius of theimage-side surface of the seventh lens element on an optical axis iscloser to the object side of the photographing system than anintersection P2 of the object-side surface of the seventh lens elementand the optical axis. Therefore, it is favorable for correcting thedistortion at the peripheral region of the image. As seen in FIG. 17,which shows a schematic view of a projection of a position of a maximumeffective radius of an image-side surface of a seventh lens element onan optical axis and an intersection of an object-side surface of aseventh lens element and the optical axis in FIG. 5.

When a focal length of the photographing system is f, a curvature radiusof the image-side surface of the sixth lens element is R12, a curvatureradius of the object-side surface of the seventh lens element is R13,the following condition is satisfied: 0.30<(f/R12)−(f/R13). Therefore,it is favorable for effectively allocating the curvatures of the sixthlens element and the seventh lens element so as to reduce thesensitivity of the photographing system and increase the manufacturingyield rate. Preferably, the following condition is satisfied:0.40<(f/R12)−(f/R13)<3.5. More preferably, the following condition issatisfied: 0.50<(f/R12)−(f/R13)<3.0.

When an Abbe number of the first lens element is V1, an Abbe number ofthe second lens element is V2, the following condition is satisfied:25<V1−V2<45. Therefore, it is favorable for correcting the chromaticaberration of the photographing system.

When the focal length of the photographing system is f, a compositefocal length of the third lens element, the fourth lens element and thefifth lens element is f345, the following condition can be satisfied:−0.30<f/f345<0.60. Therefore, it is favorable for properly distributingthe refractive powers of the third lens element, the fourth lens elementand the fifth lens element so as to prevent the refractive power fromoverly concentrated on a single lens element, thereby avoiding excessiveaberration.

When a focal length of the x-th lens element is fx, (for example, afocal length of the first lens element is f1, a focal length of thesecond lens element is f2, a focal length of the third lens element isf3, a focal length of the fourth lens element is f4, a focal length ofthe fifth lens element is f5, a focal length of the sixth lens elementis f6, a focal length of the seventh lens element is f7), the followingconditions can be satisfied: |f1|<|fx| and |f7|<|fx|, wherein x=2, 3, 4,5, 6. Therefore, it is favorable for balancing the refractive power ofthe photographing system. Furthermore, it is favorable for correctingthe aberration of the photographing system.

When an axial distance between the object-side surface of the first lenselement and an image-side surface of the fourth lens element is Dr1r8,an axial distance between an object-side surface of the fifth lenselement and the image-side surface of the seventh lens element isDr9r14, the following condition can be satisfied: 0.75<Dr1r8/Dr9r14<1.5.Therefore, it is favorable for properly arranging the axial distancesbetween every two adjacent lens elements so as to reduce the total tracklength of the photographing system.

When the focal length of the first lens element is f1, the focal lengthof the second lens element is f2, the following condition can besatisfied: |f1/f2|<0.80. Therefore, it is favorable for reducing thetotal track length and correcting the aberration of the photographingsystem.

When an f-number of the photographing system is Fno, the followingcondition can be satisfied: Fno≦2.25. Therefore, it is favorable forreceiving sufficient incoming light so as to increase the image qualityin a low light condition with a shutter at a high speed.

When the focal length of the photographing system is f, the focal lengthof the third lens element is f3, the focal length of the fourth lenselement is f4, the focal length of the fifth lens element is f5, thefollowing condition can be satisfied: |f/f3|+|f/f4|+|f/f5|<1.5.Therefore, it is favorable for balancing the refractive power of thephotographing system so as to effectively correct the aberration andreducing the sensitivity of the photographing system.

When a sum of axial distances being respectively between every two lenselements of the first lens element, the second lens element, the thirdlens element, the fourth lens element, the fifth lens element, the sixthlens element and the seventh lens element that are adjacent to eachother is ΣAT; that is, a sum of an axial distance between the first lenselement and the second lens element, an axial distance between thesecond lens element and the third lens element, an axial distancebetween the third lens element and the fourth lens element T34, an axialdistance between the fourth lens element and the fifth lens element T45,an axial distance between the fifth lens element and the sixth lenselement and an axial distance between the sixth lens element and theseventh lens element, and the following condition can be satisfied:3.0<ΣAT/(T34+T45)<10.0. Therefore, the axial distances of the lenselements are properly arranged so that it is favorable for reducing thetotal track length of the photographing system so as to keep a compactsize thereof.

According to the present disclosure, an axial distance between the sixthlens element and the seventh lens element can be the largest among theaxial distances being respectively between every two lens elements ofthe first lens element, the second lens element, the third lens element,the fourth lens element, the fifth lens element, the sixth lens elementand the seventh lens element that are adjacent to each other. Therefore,it is favorable for tightly arranging the lens elements so as to reducethe total track length of the photographing system, thereby keeping thephotographing system in a compact size.

When the Abbe number of the second lens element is V2, the followingcondition can be satisfied: 10<V2<30. Therefore, it is favorable forcorrecting the chromatic aberration of the photographing system.

According to the present disclosure, an aperture stop can be configuredas a front stop or a middle stop. A front stop disposed between animaged object and the first lens element can produce a telecentriceffect by providing a longer distance between an exit pupil of thephotographing system and the image surface and thereby improving theimage-sensing efficiency of an image sensor (for example, CCD or CMOS).A middle stop disposed between the first lens element and the imagesurface is favorable for enlarging the view angle and thereby provides awider field of view.

According to the present disclosure, the lens elements of thephotographing system can be made of glass or plastic material. When thelens elements are made of glass material, the refractive powerdistribution of the photographing system may be more flexible to design.When the lens elements are made of plastic material, the manufacturingcost can be effectively reduced. Furthermore, surfaces of each lenselement can be arranged to be aspheric, since the aspheric surface ofthe lens element is easy to form a shape other than spherical surface soas to have more controllable variables for eliminating the aberrationthereof, and to further decrease the required number of the lenselements. Therefore, the total track length of the photographing systemcan also be reduced.

According to the present disclosure, each of an object-side surface andan image-side surface has a paraxial region and an off-axis region. Theparaxial region refers to the region of the surface where light raystravel close to the optical axis, and the off-axis region refers to theregion of the surface away from the paraxial region. Particularly, whenthe lens element has a convex surface, it indicates that the surface isconvex in the paraxial region thereof; when the lens element has aconcave surface, it indicates that the surface is concave in theparaxial region thereof. Moreover, when a region of refractive power orfocus of a lens element is not defined, it indicates that the region ofrefractive power or focus of the lens element is in the paraxial regionthereof.

According to the present disclosure, an image surface of thephotographing system, based on the corresponding image sensor, can beflat or curved, especially a curved surface being concave facing towardsthe object side of the photographing system.

According to the present disclosure, the photographing system caninclude at least one stop, such as an aperture stop, a glare stop or afield stop. Said glare stop or said field stop is set for eliminatingthe stray light and thereby improving the image quality thereof.

According to the present disclosure, an image capturing unit isprovided. The image capturing unit includes the photographing systemaccording to the aforementioned photographing system of the presentdisclosure, and an image sensor, wherein the image sensor is disposed onthe image side of the aforementioned photographing system, that is, theimage sensor can be disposed on or near an image surface of theaforementioned photographing system. In some embodiments, the imagecapturing unit can further include a barrel member, a holding member ora combination thereof.

In FIG. 18, FIG. 19, and FIG. 20, an image capturing device 10 may beinstalled in, but not limited to, an electronic device, including asmart phone (FIG. 18), a tablet personal computer (FIG. 19) or awearable device (FIG. 20). The electronic devices shown in the figuresare only exemplary for showing the image capturing device of presentdisclosure installed in an electronic device and are not limitedthereto. In some embodiments, the electronic device can further include,but not limited to, a display unit, a control unit, a storage unit, arandom access memory unit (RAM), a read only memory unit (ROM) or acombination thereof.

According to the present disclosure, the photographing system can beoptionally applied to moving focus optical systems. Furthermore, thephotographing system is featured with good capability in aberrationcorrections resulting high image quality, and can be applied to 3D(three-dimensional) image capturing applications, in products such asdigital cameras, mobile devices, digital tablets, wearable devices,smart televisions, network surveillance devices, motion sensing inputdevices, dashboard cameras, vehicle backup cameras and other electronicimaging devices. According to the above description of the presentdisclosure, the following specific embodiments are provided for furtherexplanation.

1st Embodiment

FIG. 1 is a schematic view of an image capturing unit according to the1st embodiment of the present disclosure. FIG. 2 shows, in order fromleft to right, spherical aberration curves, astigmatic field curves anda distortion curve of the image capturing unit according to the 1stembodiment. In FIG. 1, the image capturing unit includes thephotographing system (its reference numeral is omitted) of the presentdisclosure and an image sensor 195. The photographing system includes,in order from an object side to an image side, an aperture stop 100, afirst lens element 110, a second lens element 120, a third lens element130, a fourth lens element 140, a fifth lens element 150, a sixth lenselement 160, a seventh lens element 170, an IR-cut filter 180 and animage surface 190, wherein the photographing system has a total of sevenlens elements (110-170) with refractive power. The first lens element110, the second lens element 120, the third lens element 130, the fourthlens element 140, the fifth lens element 150, the sixth lens element 160and the seventh lens element 170 are all stationary relative to oneanother in a paraxial region thereof. There is an air gap in a paraxialregion between every two of the first lens element 110, the second lenselement 120, the third lens element 130, the fourth lens element 140,the fifth lens element 150, the sixth lens element 160 and the seventhlens element 170 that are adjacent to each other.

The first lens element 110 with positive refractive power has anobject-side surface 111 being convex in a paraxial region thereof and animage-side surface 112 being concave in a paraxial region thereof. Thefirst lens element 110 is made of plastic material and has theobject-side surface 111 and the image-side surface 112 being bothaspheric.

The second lens element 120 with negative refractive power has anobject-side surface 121 being convex in a paraxial region thereof and animage-side surface 122 being concave in a paraxial region thereof. Thesecond lens element 120 is made of plastic material and has theobject-side surface 121 and the image-side surface 122 being bothaspheric.

The third lens element 130 with negative refractive power has anobject-side surface 131 being convex in a paraxial region thereof and animage-side surface 132 being concave in a paraxial region thereof. Thethird lens element 130 is made of plastic material and has theobject-side surface 131 and the image-side surface 132 being bothaspheric.

The fourth lens element 140 with positive refractive power has anobject-side surface 141 being convex in a paraxial region thereof and animage-side surface 142 being convex in a paraxial region thereof. Thefourth lens element 140 is made of plastic material and has theobject-side surface 141 and the image-side surface 142 being bothaspheric.

The fifth lens element 150 with negative refractive power has anobject-side surface 151 being concave in a paraxial region thereof andan image-side surface 152 being convex in a paraxial region thereof. Thefifth lens element 150 is made of plastic material and has theobject-side surface 151 and the image-side surface 152 being bothaspheric.

The sixth lens element 160 with positive refractive power has anobject-side surface 161 being convex in a paraxial region thereof and animage-side surface 162 being concave in a paraxial region thereof. Thesixth lens element 160 is made of plastic material and has theobject-side surface 161 and the image-side surface 162 being bothaspheric. The object-side surface 161 of the sixth lens element 160 hasat least one concave shape in an off-axis region thereof. The image-sidesurface 162 of the sixth lens element 160 has at least one convex shapein an off-axis region thereof.

The seventh lens element 170 with negative refractive power has anobject-side surface 171 being concave in a paraxial region thereof andan image-side surface 172 being concave in a paraxial region thereof.The seventh lens element 170 is made of plastic material and has theobject-side surface 171 and the image-side surface 172 being bothaspheric. The image-side surface 172 of the seventh lens element 170 hasat least one convex shape in an off-axis region thereof.

The IR-cut filter 180 is made of glass and located between the seventhlens element 170 and the image surface 190, and will not affect thefocal length of the photographing system. The image sensor 195 isdisposed on or near the image surface 190 of the photographing system.

The equation of the aspheric surface profiles of the aforementioned lenselements of the 1st embodiment is expressed as follows:

${{X(Y)} = {{\left( {Y^{2}\text{/}R} \right)\text{/}\left( {1 + {{sqrt}\left( {1 - {\left( {1 + k} \right) \times \left( {Y\text{/}R} \right)^{2}}} \right)}} \right)} + {\sum\limits_{i}{({Ai}) \times \left( Y^{i} \right)}}}},$where,

X is the relative distance between a point on the aspheric surfacespaced at a distance Y from an optical axis and the tangential plane atthe aspheric surface vertex on the optical axis;

Y is the vertical distance from the point on the aspheric surface to theoptical axis;

R is the curvature radius;

k is the conic coefficient; and

Ai is the i-th aspheric coefficient, and in the embodiments, i may be,but is not limited to, 4, 6, 8, 10, 12, 14 and 16.

In the photographing system of the image capturing unit according to the1st embodiment, when a focal length of the photographing system in theparaxial region thereof is f, an f-number of the photographing system isFno, and half of a maximal field of view of the photographing system isHFOV, these parameters have the following values: f=5.19 millimeters(mm); Fno=1.85; and HFOV=36.0 degrees.

When an Abbe number of the second lens element 120 is V2, the followingcondition is satisfied: V2=23.5.

When an Abbe number of the first lens element 110 is V1, the Abbe numberof the second lens element 120 is V2, the following condition issatisfied: V1−V2=32.40.

When an axial distance between the object-side surface 111 of the firstlens element 110 and the image-side surface 142 of the fourth lenselement 140 is Dr1r8, an axial distance between the object-side surface151 of the fifth lens element 150 and the image-side surface 172 of theseventh lens element 170 is Dr9r14, the following condition issatisfied: Dr1r8/Dr9r14=0.94.

When a sum of axial distances between every two lens elements adjacentto each other among the first lens element 110 through the seventh lenselement 170 is ΣAT, an axial distance between the third lens element 130and the fourth lens element 140 is T34, an axial distance between thefourth lens element 140 and the fifth lens element 150 is T45, thefollowing condition is satisfied: ΣAT/(T34+T45)=6.17.

When the focal length of the photographing system is f, a curvatureradius of the image-side surface 162 of the sixth lens element 160 isR12, a curvature radius of the object-side surface 171 of the seventhlens element 170 is R13, the following condition is satisfied:(f/R12)−(f/R13)=0.32.

When a focal length of the first lens element 110 is f1, a focal lengthof the second lens element 120 is f2, the following condition issatisfied: |f1/f2|=0.49.

When the focal length of the photographing system is f, a focal lengthof the third lens element 130 is f3, a focal length of the fourth lenselement 140 is f4, a focal length of the fifth lens element 150 is f5,the following condition is satisfied:|f/f3|+|f/f4|+|f/f5|=1.16.

When the focal length of the photographing system is f, a compositefocal length of the third lens element 130, the fourth lens element 140and the fifth lens element 150 is f345, the following condition issatisfied: f/f345=0.20.

The detailed optical data of the 1st embodiment are shown in Table 1 andthe aspheric surface data are shown in Table 2 below.

TABLE 1 1st Embodiment f = 5.19 mm, Fno = 1.85, HFOV = 36.0 deg. FocalSurface# Curvature Radius Thickness Material Index Abbe # Length 0Object Plano Infinity 1 Ape. Stop Plano −0.470 2 Lens 1 2.350 (ASP)0.704 Plastic 1.544 55.9 4.84 3 19.630 (ASP) 0.056 4 Lens 2 4.635 (ASP)0.280 Plastic 1.639 23.5 −9.80 5 2.601 (ASP) 0.405 6 Lens 3 5.782 (ASP)0.325 Plastic 1.544 55.9 −58.00 7 4.790 (ASP) 0.207 8 Lens 4 7.365 (ASP)0.709 Plastic 1.544 55.9 7.61 9 −9.130 (ASP) 0.095 10 Lens 5 −2.495(ASP) 0.387 Plastic 1.639 23.5 −13.50 11 −3.723 (ASP) 0.287 12 Lens 63.351 (ASP) 0.631 Plastic 1.544 55.9 7.34 13 19.398 (ASP) 0.814 14 Lens7 −98.801 (ASP) 0.731 Plastic 1.535 55.7 −4.56 15 2.510 (ASP) 0.500 16IR-cut filter Plano 0.210 Glass 1.517 64.2 — 17 Plano 0.240 18 ImagePlano — Note: Reference wavelength is 587.6 nm (d-line).

TABLE 2 Aspheric Coefficients Surface # 2 3 4 5 6 k =  2.1296E−01−8.6527E+01 −6.5133E+00 −1.5120E+01 −7.0244E+01 A4 =  9.2646E−04−4.1334E−02 −7.7191E−02  5.1947E−02 −3.2861E−03 A6 = −1.7176E−03 6.4590E−02  8.8016E−02 −4.6694E−02 −1.5821E−02 A8 =  3.9088E−03−5.3306E−02 −6.0224E−02  5.6103E−02  6.5798E−03 A10 = −4.1754E−03 2.6270E−02  2.7049E−02 −3.6019E−02 −1.2907E−03 A12 =  2.1577E−03−6.5197E−03 −6.3011E−03  1.3389E−02  1.2607E−04 A14 = −4.1047E−04 5.0076E−04  3.7876E−04 −2.0674E−03 −1.4031E−04 Surface # 7 8 9 10 11 k= −4.1559E+01 −9.0000E+01  2.4944E+01 −1.0062E+00 −2.2648E+01 A4 =−2.5121E−02 −3.7711E−02 −6.5636E−02  5.8191E−03 −5.5709E−02 A6 =−4.7742E−03 −6.1624E−03  3.0189E−02  5.3471E−02  6.0609E−02 A8 = 7.7914E−04 −1.5145E−03 −1.2640E−02 −5.3689E−02 −3.7827E−02 A10 = 2.5432E−04  4.3097E−04 −8.6636E−03  2.6423E−02  1.4415E−02 A12 =−2.2216E−04  3.5475E−04  1.1088E−02 −6.4021E−03 −2.9679E−03 A14 = — —−4.1288E−03  5.4119E−04  2.4471E−04 A16 = — —  5.2570E−04 — — Surface #12 13 14 15 k = −1.4368E+01  2.1011E+01 −9.0000E+01 −3.4442E+00 A4 =−1.7418E−03  1.3035E−03 −8.9813E−02 −6.6083E−02 A6 = −7.4522E−03−8.6064E−03  8.9513E−03  1.9131E−02 A8 =  9.9732E−04  2.6197E−03 5.5542E−03 −3.9911E−03 A10 = −9.6787E−04 −1.2475E−03 −3.0335E−03 5.3163E−04 A12 =  3.6010E−04  3.0127E−04  5.9841E−04 −4.3138E−05 A14 =−4.0204E−05 −2.3092E−05 −4.2052E−05  1.9337E−06 A16 = — —  2.7771E−07−3.6970E−08

In Table 1, the curvature radius, the thickness and the focal length areshown in millimeters (mm). Surface numbers 0-18 represent the surfacessequentially arranged from the object-side to the image-side along theoptical axis. In Table 2, k represents the conic coefficient of theequation of the aspheric surface profiles. A4-A16 represent the asphericcoefficients ranging from the 4th order to the 16th order. The tablespresented below for each embodiment are the corresponding schematicparameter and aberration curves, and the definitions of the tables arethe same as Table 1 and Table 2 of the 1st embodiment. Therefore, anexplanation in this regard will not be provided again.

2nd Embodiment

FIG. 3 is a schematic view of an image capturing unit according to the2nd embodiment of the present disclosure. FIG. 4 shows, in order fromleft to right, spherical aberration curves, astigmatic field curves anda distortion curve of the image capturing unit according to the 2ndembodiment. In FIG. 3, the image capturing unit includes thephotographing system (its reference numeral is omitted) of the presentdisclosure and an image sensor 295. The photographing system includes,in order from an object side to an image side an aperture stop 200, afirst lens element 210, a second lens element 220, a third lens element230, a fourth lens element 240, a fifth lens element 250, a sixth lenselement 260, a seventh lens element 270, an IR-cut filter 280 and animage surface 290, wherein the photographing system has a total of sevenlens elements (210-270) with refractive power. The first lens element210, the second lens element 220, the third lens element 230, the fourthlens element 240, the fifth lens element 250, the sixth lens element 260and the seventh lens element 270 are all stationary relative to oneanother in a paraxial region thereof. There is an air gap in a paraxialregion between every two of the first lens element 210, the second lenselement 220, the third lens element 230, the fourth lens element 240,the fifth lens element 250, the sixth lens element 260 and the seventhlens element 270 that are adjacent to each other.

The first lens element 210 with positive refractive power has anobject-side surface 211 being convex in a paraxial region thereof and animage-side surface 212 being convex in a paraxial region thereof. Thefirst lens element 210 is made of plastic material and has theobject-side surface 211 and the image-side surface 212 being bothaspheric.

The second lens element 220 with negative refractive power has anobject-side surface 221 being convex in a paraxial region thereof and animage-side surface 222 being concave in a paraxial region thereof. Thesecond lens element 220 is made of plastic material and has theobject-side surface 221 and the image-side surface 222 being bothaspheric.

The third lens element 230 with negative refractive power has anobject-side surface 231 being convex in a paraxial region thereof and animage-side surface 232 being concave in a paraxial region thereof. Thethird lens element 230 is made of plastic material and has theobject-side surface 231 and the image-side surface 232 being bothaspheric.

The fourth lens element 240 with positive refractive power has anobject-side surface 241 being convex in a paraxial region thereof and animage-side surface 242 being convex in a paraxial region thereof. Thefourth lens element 240 is made of plastic material and has theobject-side surface 241 and the image-side surface 242 being bothaspheric.

The fifth lens element 250 with positive refractive power has anobject-side surface 251 being concave in a paraxial region thereof andan image-side surface 252 being convex in a paraxial region thereof. Thefifth lens element 250 is made of plastic material and has theobject-side surface 251 and the image-side surface 252 being bothaspheric.

The sixth lens element 260 with positive refractive power has anobject-side surface 261 being convex in a paraxial region thereof and animage-side surface 262 being concave in a paraxial region thereof. Thesixth lens element 260 is made of plastic material and has theobject-side surface 261 and the image-side surface 262 being bothaspheric. The object-side surface 261 of the sixth lens element 260 hasat least one concave shape in an off-axis region thereof. The image-sidesurface 262 of the sixth lens element 260 has at least one convex shapein an off-axis region thereof.

The seventh lens element 270 with negative refractive power has anobject-side surface 271 being concave in a paraxial region thereof andan image-side surface 272 being concave in a paraxial region thereof.The seventh lens element 270 is made of plastic material and has theobject-side surface 271 and the image-side surface 272 being bothaspheric. The image-side surface 272 of the seventh lens element 270 hasat least one convex shape in an off-axis region thereof.

The IR-cut filter 280 is made of glass and located between the seventhlens element 270 and the image surface 290, and will not affect thefocal length of the photographing system. The image sensor 295 isdisposed on or near the image surface 290 of the photographing system.

The detailed optical data of the 2nd embodiment are shown in Table 3 andthe aspheric surface data are shown in Table 4 below.

TABLE 3 2nd Embodiment f = 5.06 mm, Fno = 2.05, HFOV = 37.2 deg. FocalSurface# Curvature Radius Thickness Material Index Abbe # Length 0Object Plano Infinity 1 Ape. Stop Plano −0.357 2 Lens 1 2.330 (ASP)0.614 Plastic 1.530 55.8 4.31 3 −99.868 (ASP) 0.035 4 Lens 2 3.455 (ASP)0.280 Plastic 1.645 22.5 −7.88 5 1.991 (ASP) 0.494 6 Lens 3 8.603 (ASP)0.300 Plastic 1.645 22.5 −34.31 7 6.109 (ASP) 0.100 8 Lens 4 8.095 (ASP)0.876 Plastic 1.544 55.9 8.12 9 −9.349 (ASP) 0.311 10 Lens 5 −3.155(ASP) 0.280 Plastic 1.645 22.5 162.29 11 −3.169 (ASP) 0.043 12 Lens 64.675 (ASP) 0.626 Plastic 1.544 55.9 14.65 13 10.771 (ASP) 0.750 14 Lens7 −98.801 (ASP) 0.698 Plastic 1.544 55.9 −4.50 15 2.515 (ASP) 0.450 16IR-cut filter Plano 0.300 Glass 1.517 64.2 — 17 Plano 0.200 18 ImagePlano — Note: Reference wavelength is 587.6 nm (d-line).

TABLE 4 Aspheric Coefficients Surface # 2 3 4 5 6 k =  2.3037E−01 4.0000E+01 −1.8898E+00 −6.3424E+00 −9.0000E+01 A4 =  5.6921E−05−1.0429E−02 −6.9298E−02  2.9701E−02 −1.1492E−02 A6 =  4.8418E−04 4.9295E−02  9.2487E−02 −3.1419E−03 −1.2996E−02 A8 =  6.6822E−04−5.4086E−02 −8.6006E−02  1.3646E−02  2.7319E−03 A10 = −3.4212E−03 2.9751E−02  4.9885E−02 −1.4922E−02 −6.5651E−04 A12 =  3.7758E−03−7.2292E−03 −1.6830E−02  7.2981E−03 −1.2768E−03 A14 = −1.2641E−03 4.8057E−06  2.1011E−03 −1.4579E−03  2.8886E−04 Surface # 7 8 9 10 11 k= −4.3634E+01 −9.0000E+01  1.4539E+01  5.3180E−01 −1.5614E+01 A4 =−2.9931E−02 −2.5050E−02 −6.7774E−02 −4.5438E−02 −3.7227E−02 A6 =−6.1899E−03  1.0299E−03  3.4035E−02  1.6434E−01  8.6236E−02 A8 =−1.6139E−03 −3.6814E−04 −1.2092E−02 −1.5430E−01 −6.8550E−02 A10 = 1.0947E−03  2.3267E−03 −9.0795E−03  6.9007E−02  2.5335E−02 A12 =−2.5820E−04 −3.8122E−04  1.0919E−02 −1.5404E−02 −4.4538E−03 A14 = — —−4.0510E−03  1.3508E−03  3.0174E−04 A16 = — —  5.4744E−04 — — Surface #12 13 14 15 k =  6.8937E−01  1.7110E+01 −9.0000E+01 −2.9948E+00 A4 = 3.7883E−02  3.0918E−02 −7.6728E−02 −6.9917E−02 A6 = −8.9295E−02−5.0912E−02  1.7296E−03  1.9180E−02 A8 =  5.1711E−02  2.1952E−02 5.5386E−03 −4.1010E−03 A10 = −1.8510E−02 −5.9551E−03 −2.5601E−03 5.8622E−04 A12 =  3.4161E−03  8.7926E−04  6.1264E−04 −5.1745E−05 A14 =−2.4545E−04 −5.0842E−05 −6.9372E−05  2.5142E−06 A16 = — —  2.9195E−06−5.1815E−08

In the 2nd embodiment, the equation of the aspheric surface profiles ofthe aforementioned lens elements is the same as the equation of the 1stembodiment. Also, the definitions of these parameters shown in thefollowing table are the same as those stated in the 1st embodiment withcorresponding values for the 2nd embodiment, so an explanation in thisregard will not be provided again.

Moreover, these parameters can be calculated from Table 3 and Table 4 asthe following values and satisfy the following conditions:

2nd Embodiment f [mm] 5.06 ΣAT/(T34 + T45) 4.22 Fno 2.05 (f/R12) −(f/R13) 0.52 HFOV [deg.] 37.2 |f1/f2| 0.55 V2 22.5 |f/f3| + |f/f4| +|f/f5| 0.80 V1 − V2 33.30 f/f345 0.49 Dr1r8/Dr9r14 1.13

3rd Embodiment

FIG. 5 is a schematic view of an image capturing unit according to the3rd embodiment of the present disclosure. FIG. 6 shows, in order fromleft to right, spherical aberration curves, astigmatic field curves anda distortion curve of the image capturing unit according to the 3rdembodiment. In FIG. 5, the image capturing unit includes thephotographing system (its reference numeral is omitted) of the presentdisclosure and an image sensor 395. The photographing system includes,in order from an object side to an image side, a first lens element 310,an aperture stop 300, a second lens element 320, a third lens element330, a fourth lens element 340, a fifth lens element 350, a sixth lenselement 360, a seventh lens element 370, an IR-cut filter 380 and animage surface 390, wherein the photographing system has a total of sevenlens elements (310-370) with refractive power. The first lens element310, the second lens element 320, the third lens element 330, the fourthlens element 340, the fifth lens element 350, the sixth lens element 360and the seventh lens element 370 are all stationary relative to oneanother in a paraxial region thereof. There is an air gap in a paraxialregion between every two of the first lens element 310, the second lenselement 320, the third lens element 330, the fourth lens element 340,the fifth lens element 350, the sixth lens element 360 and the seventhlens element 370 that are adjacent to each other.

The first lens element 310 with positive refractive power has anobject-side surface 311 being convex in a paraxial region thereof and animage-side surface 312 being convex in a paraxial region thereof. Thefirst lens element 310 is made of plastic material and has theobject-side surface 311 and the image-side surface 312 being bothaspheric.

The second lens element 320 with negative refractive power has anobject-side surface 321 being convex in a paraxial region thereof and animage-side surface 322 being concave in a paraxial region thereof. Thesecond lens element 320 is made of plastic material and has theobject-side surface 321 and the image-side surface 322 being bothaspheric.

The third lens element 330 with negative refractive power has anobject-side surface 331 being convex in a paraxial region thereof and animage-side surface 332 being concave in a paraxial region thereof. Thethird lens element 330 is made of plastic material and has theobject-side surface 331 and the image-side surface 332 being bothaspheric.

The fourth lens element 340 with positive refractive power has anobject-side surface 341 being convex in a paraxial region thereof and animage-side surface 342 being convex in a paraxial region thereof. Thefourth lens element 340 is made of plastic material and has theobject-side surface 341 and the image-side surface 342 being bothaspheric.

The fifth lens element 350 with positive refractive power has anobject-side surface 351 being concave in a paraxial region thereof andan image-side surface 352 being convex in a paraxial region thereof. Thefifth lens element 350 is made of plastic material and has theobject-side surface 351 and the image-side surface 352 being bothaspheric.

The sixth lens element 360 with negative refractive power has anobject-side surface 361 being convex in a paraxial region thereof and animage-side surface 362 being concave in a paraxial region thereof. Thesixth lens element 360 is made of plastic material and has theobject-side surface 361 and the image-side surface 362 being bothaspheric. The object-side surface 361 of the sixth lens element 360 hasat least one concave shape in an off-axis region thereof. The image-sidesurface 362 of the sixth lens element 360 has at least one convex shapein an off-axis region thereof.

The seventh lens element 370 with negative refractive power has anobject-side surface 371 being concave in a paraxial region thereof andan image-side surface 372 being concave in a paraxial region thereof.The seventh lens element 370 is made of plastic material and has theobject-side surface 371 and the image-side surface 372 being bothaspheric. The image-side surface 372 of the seventh lens element 370 hasat least one convex shape in an off-axis region thereof.

The IR-cut filter 380 is made of glass and located between the seventhlens element 370 and the image surface 390, and will not affect thefocal length of the photographing system. The image sensor 395 isdisposed on or near the image surface 390 of the photographing system.

The detailed optical data of the 3rd embodiment are shown in Table 5 andthe aspheric surface data are shown in Table 6 below.

TABLE 5 3rd Embodiment f = 5.05 mm, Fno = 2.12, HFOV = 37.2 deg. FocalSurface# Curvature Radius Thickness Material Index Abbe # Length 0Object Plano Infinity 1 Lens 1 2.363 (ASP) 0.708 Plastic 1.544 55.9 4.272 −117.394 (ASP) 0.012 3 Ape. Stop Plano 0.038 4 Lens 2 3.623 (ASP)0.284 Plastic 1.640 23.3 −7.39 5 1.988 (ASP) 0.372 6 Lens 3 7.772 (ASP)0.300 Plastic 1.640 23.3 −25.16 7 5.162 (ASP) 0.100 8 Lens 4 6.938 (ASP)0.979 Plastic 1.544 55.9 6.45 9 −6.758 (ASP) 0.292 10 Lens 5 −2.872(ASP) 0.350 Plastic 1.544 55.9 10.72 11 −2.007 (ASP) 0.157 12 Lens 632.019 (ASP) 0.608 Plastic 1.640 23.3 −23.17 13 10.057 (ASP) 0.802 14Lens 7 −82.431 (ASP) 0.415 Plastic 1.544 55.9 −4.81 15 2.708 (ASP) 0.50016 IR-cut filter Plano 0.300 Glass 1.517 64.2 — 17 Plano 0.149 18 ImagePlano — Note: Reference wavelength is 587.6 nm (d-line).

TABLE 6 Aspheric Coefficients Surface # 1 2 4 5 6 k =  1.8639E−01−9.0000E+01 −2.8786E+00 −6.3812E+00 −9.0000E+01 A4 = −1.4547E−03−1.4382E−02 −7.6780E−02  2.7581E−02 −1.1032E−02 A6 =  1.6567E−03 4.8845E−02  1.0913E−01 −7.9756E−03 −1.1221E−02 A8 =  8.0908E−04−5.3153E−02 −1.2654E−01  1.3489E−02  1.5115E−03 A10 = −3.8861E−03 2.9707E−02  9.6527E−02 −1.3756E−02 −1.0351E−03 A12 =  3.2553E−03−7.4228E−03 −4.1316E−02  8.2174E−03 −1.2075E−03 A14 = −8.7053E−04 2.1968E−04  7.0858E−03 −2.1297E−03  7.4240E−04 Surface # 7 8 9 10 11 k= −4.3704E+01 −9.0000E+01  1.2045E+01  6.5326E−01 −9.7812E+00 A4 =−2.5343E−02 −1.7664E−02 −5.9060E−02 −6.5669E−02 −8.0528E−02 A6 =−3.2159E−03  1.6171E−03  3.2915E−02  1.7126E−01  1.4507E−01 A8 =−1.3030E−03 −4.0991E−04 −1.2662E−02 −1.3986E−01 −1.0321E−01 A10 = 1.0979E−03  2.3042E−03 −9.2391E−03  5.5561E−02  3.7232E−02 A12 = 2.1290E−05 −4.2535E−04  1.0898E−02 −1.0919E−02 −6.6608E−03 A14 = — —−4.0396E−03  7.9904E−04  4.6905E−04 A16 = — —  5.5861E−04 — — Surface #12 13 14 15 k = −8.9856E+01  1.3514E+01 −9.0000E+01 −5.8292E+00 A4 = 4.2157E−02  1.2362E−03 −9.3623E−02 −6.7610E−02 A6 = −5.4070E−02−1.7853E−02  1.7505E−02  1.7722E−02 A8 =  2.0695E−02  6.0974E−03−7.6279E−05 −3.4673E−03 A10 = −5.2610E−03 −1.2973E−03 −5.3932E−04 4.3256E−04 A12 =  5.2700E−04  1.5242E−04  1.1175E−04 −3.2327E−05 A14 = 6.4357E−06 −7.0517E−06 −1.0204E−05  1.3064E−06 A16 = — —  3.6269E−07−2.2701E−08

In the 3rd embodiment, the equation of the aspheric surface profiles ofthe aforementioned lens elements is the same as the equation of the 1stembodiment. Also, the definitions of these parameters shown in thefollowing table are the same as those stated in the 1st embodiment withcorresponding values for the 3rd embodiment, so an explanation in thisregard will not be provided again.

Moreover, these parameters can be calculated from Table 5 and Table 6 asthe following values and satisfy the following conditions:

3rd Embodiment f [mm] 5.05 ΣAT/(T34 + T45) 4.52 Fno 2.12 (f/R12) −(f/R13) 0.56 HFOV [deg.] 37.2 |f1/f2| 0.58 V2 23.3 |f/f3| + |f/f4| +|f/f5| 1.45 V1 − V2 32.60 f/f345 0.99 Dr1r8/Dr9r14 1.20

4th Embodiment

FIG. 7 is a schematic view of an image capturing unit according to the4th embodiment of the present disclosure. FIG. 8 shows, in order fromleft to right, spherical aberration curves, astigmatic field curves anda distortion curve of the image capturing unit according to the 4thembodiment. In FIG. 7, the image capturing unit includes thephotographing system (its reference numeral is omitted) of the presentdisclosure and an image sensor 495. The photographing system includes,in order from an object side to an image side, a first lens element 410,an aperture stop 400, a second lens element 420, a third lens element430, a fourth lens element 440, a fifth lens element 450, a sixth lenselement 460, a seventh lens element 470, an IR-cut filter 480 and animage surface 490, wherein the photographing system has a total of sevenlens elements (410-470) with refractive power. The first lens element410, the second lens element 420, the third lens element 430, the fourthlens element 440, the fifth lens element 450, the sixth lens element 460and the seventh lens element 470 are all stationary relative to oneanother in a paraxial region thereof. There is an air gap in a paraxialregion between every two of the first lens element 410, the second lenselement 420, the third lens element 430, the fourth lens element 440,the fifth lens element 450, the sixth lens element 460 and the seventhlens element 470 that are adjacent to each other.

The first lens element 410 with positive refractive power has anobject-side surface 411 being convex in a paraxial region thereof and animage-side surface 412 being convex in a paraxial region thereof. Thefirst lens element 410 is made of plastic material and has theobject-side surface 411 and the image-side surface 412 being bothaspheric.

The second lens element 420 with negative refractive power has anobject-side surface 421 being convex in a paraxial region thereof and animage-side surface 422 being concave in a paraxial region thereof. Thesecond lens element 420 is made of plastic material and has theobject-side surface 421 and the image-side surface 422 being bothaspheric.

The third lens element 430 with positive refractive power has anobject-side surface 431 being convex in a paraxial region thereof and animage-side surface 432 being concave in a paraxial region thereof. Thethird lens element 430 is made of plastic material and has theobject-side surface 431 and the image-side surface 432 being bothaspheric.

The fourth lens element 440 with positive refractive power has anobject-side surface 441 being convex in a paraxial region thereof and animage-side surface 442 being concave in a paraxial region thereof. Thefourth lens element 440 is made of plastic material and has theobject-side surface 441 and the image-side surface 442 being bothaspheric.

The fifth lens element 450 with positive refractive power has anobject-side surface 451 being concave in a paraxial region thereof andan image-side surface 452 being convex in a paraxial region thereof. Thefifth lens element 450 is made of plastic material and has theobject-side surface 451 and the image-side surface 452 being bothaspheric.

The sixth lens element 460 with negative refractive power has anobject-side surface 461 being convex in a paraxial region thereof and animage-side surface 462 being concave in a paraxial region thereof. Thesixth lens element 460 is made of plastic material and has theobject-side surface 461 and the image-side surface 462 being bothaspheric. The object-side surface 461 of the sixth lens element 460 hasat least one concave shape in an off-axis region thereof. The image-sidesurface 462 of the sixth lens element 460 has at least one convex shapein an off-axis region thereof.

The seventh lens element 470 with negative refractive power has anobject-side surface 471 being concave in a paraxial region thereof andan image-side surface 472 being concave in a paraxial region thereof.The seventh lens element 470 is made of plastic material and has theobject-side surface 471 and the image-side surface 472 being bothaspheric.

The IR-cut filter 480 is made of glass and located between the seventhlens element 470 and the image surface 490, and will not affect thefocal length of the photographing system. The image sensor 495 isdisposed on or near the image surface 490 of the photographing system.

The detailed optical data of the 4th embodiment are shown in Table 7 andthe aspheric surface data are shown in Table 8 below.

TABLE 7 4th Embodiment f = 5.01 mm, Fno = 2.25, HFOV = 37.3 deg. FocalSurface# Curvature Radius Thickness Material Index Abbe # Length 0Object Plano Infinity 1 Lens 1 1.902 (ASP) 0.720 Plastic 1.544 55.9 3.482 −494.868 (ASP) −0.021 3 Ape. Stop Plano 0.075 4 Lens 2 14.834 (ASP)0.280 Plastic 1.639 23.5 −5.71 5 2.907 (ASP) 0.243 6 Lens 3 4.761 (ASP)0.310 Plastic 1.544 55.9 122.46 7 5.009 (ASP) 0.275 8 Lens 4 3.535 (ASP)0.261 Plastic 1.639 23.5 64.24 9 3.757 (ASP) 0.527 10 Lens 5 −5.784(ASP) 0.350 Plastic 1.544 55.9 6.11 11 −2.155 (ASP) 0.100 12 Lens 610.815 (ASP) 0.252 Plastic 1.544 55.9 −50.15 13 7.682 (ASP) 0.828 14Lens 7 −123.133 (ASP) 0.350 Plastic 1.535 55.7 −4.05 15 2.208 (ASP)0.500 16 IR-cut filter Plano 0.300 Glass 1.517 64.2 — 17 Plano 0.149 18Image Plano — Note: Reference wavelength is 587.6 nm (d-line).

TABLE 8 Aspheric Coefficients Surface # 1 2 4 5 6 k =  2.8365E−02 4.0000E+01  7.4888E+01 −5.4258E+00 −9.0008E+00 A4 = −1.9682E−03−4.9986E−02 −5.3683E−02  1.3309E−02 −1.3494E−02 A6 = −1.2153E−02 5.6258E−02  6.9567E−02  2.1902E−02 −2.6631E−02 A8 =  6.2481E−03−5.1966E−02 −1.6440E−02  2.8009E−03 −4.8479E−03 A10 = −6.2637E−03 2.6345E−02 −1.4315E−02 −1.7157E−03  1.8765E−03 A12 = −1.1261E−03−7.7454E−03  2.1868E−02  1.2151E−02  1.3261E−03 A14 =  3.5097E−04 6.1149E−04 −7.4544E−03 −5.0219E−03  2.8638E−03 Surface # 7 8 9 10 11 k= −5.8696E+01 −2.1720E+01 −1.4572E+01  9.4370E+00 −2.6024E+00 A4 =−7.2549E−04 −8.0618E−02 −9.2390E−02 −3.8094E−02  1.9803E−02 A6 =−1.6367E−02  8.2741E−03  2.2205E−02  7.6432E−02 −2.7741E−02 A8 =−1.6498E−02 −2.0263E−03 −7.7960E−03 −6.1773E−02  4.1832E−02 A10 = 1.5069E−03 −7.2685E−04 −8.4503E−03  1.8679E−02 −2.9417E−02 A12 = 2.3710E−03 −4.6111E−04  1.1072E−02 −4.1448E−03  8.7920E−03 A14 = — —−4.0035E−03  6.5218E−04 −9.5600E−04 A16 = — —  5.7635E−04 — — Surface #12 13 14 15 k =  6.5450E+00  1.2271E+01 −1.0000E+00 −9.3112E+00 A4 = 1.5459E−01  1.3670E−01 −1.1234E−01 −8.2655E−02 A6 = −2.7727E−01−2.4390E−01  3.0671E−02  2.1042E−02 A8 =  1.6853E−01  1.4238E−01−3.3143E−03 −2.7320E−03 A10 = −5.9824E−02 −4.7479E−02  4.5884E−06 1.6236E−04 A12 =  1.1264E−02  8.3325E−03  3.7912E−05 −6.6474E−06 A14 =−8.4119E−04 −5.8689E−04 −3.7642E−06  6.2516E−07 A16 = — —  1.2206E−07−2.9975E−08

In the 4th embodiment, the equation of the aspheric surface profiles ofthe aforementioned lens elements is the same as the equation of the 1stembodiment. Also, the definitions of these parameters shown in thefollowing table are the same as those stated in the 1st embodiment withcorresponding values for the 4th embodiment, so an explanation in thisregard will not be provided again.

Moreover, these parameters can be calculated from Table 7 and Table 8 asthe following values and satisfy the following conditions:

4th Embodiment f [mm] 5.01 ΣAT/(T34 + T45) 2.53 Fno 2.25 (f/R12) −(f/R13) 0.69 HFOV [deg.] 37.3 |f1/f2| 0.61 V2 23.5 |f/f3| + |f/f4| +|f/f5| 0.94 V1 − V2 32.40 f/f345 0.88 Dr1r8/Dr9r14 1.14

5th Embodiment

FIG. 9 is a schematic view of an image capturing unit according to the5th embodiment of the present disclosure. FIG. 10 shows, in order fromleft to right, spherical aberration curves, astigmatic field curves anda distortion curve of the image capturing unit according to the 5thembodiment. In FIG. 9, the image capturing unit includes thephotographing system (its reference numeral is omitted) of the presentdisclosure and an image sensor 595. The photographing system includes,in order from an object side to an image side, an aperture stop 500, afirst lens element 510, a second lens element 520, a third lens element530, a fourth lens element 540, a fifth lens element 550, a sixth lenselement 560, a seventh lens element 570, an IR-cut filter 580 and animage surface 590, wherein the photographing system has a total of sevenlens elements (510-570) with refractive power. The first lens element510, the second lens element 520, the third lens element 530, the fourthlens element 540, the fifth lens element 550, the sixth lens element 560and the seventh lens element 570 are all stationary relative to oneanother in a paraxial region thereof. There is an air gap in a paraxialregion between every two of the first lens element 510, the second lenselement 520, the third lens element 530, the fourth lens element 540,the fifth lens element 550, the sixth lens element 560 and the seventhlens element 570 that are adjacent to each other.

The first lens element 510 with positive refractive power has anobject-side surface 511 being convex in a paraxial region thereof and animage-side surface 512 being concave in a paraxial region thereof. Thefirst lens element 510 is made of plastic material and has theobject-side surface 511 and the image-side surface 512 being bothaspheric.

The second lens element 520 with negative refractive power has anobject-side surface 521 being concave in a paraxial region thereof andan image-side surface 522 being concave in a paraxial region thereof.The second lens element 520 is made of plastic material and has theobject-side surface 521 and the image-side surface 522 being bothaspheric.

The third lens element 530 with positive refractive power has anobject-side surface 531 being convex in a paraxial region thereof and animage-side surface 532 being concave in a paraxial region thereof. Thethird lens element 530 is made of plastic material and has theobject-side surface 531 and the image-side surface 532 being bothaspheric.

The fourth lens element 540 with negative refractive power has anobject-side surface 541 being convex in a paraxial region thereof and animage-side surface 542 being concave in a paraxial region thereof. Thefourth lens element 540 is made of plastic material and has theobject-side surface 541 and the image-side surface 542 being bothaspheric.

The fifth lens element 550 with positive refractive power has anobject-side surface 551 being concave in a paraxial region thereof andan image-side surface 552 being convex in a paraxial region thereof. Thefifth lens element 550 is made of plastic material and has theobject-side surface 551 and the image-side surface 552 being bothaspheric.

The sixth lens element 560 with positive refractive power has anobject-side surface 561 being convex in a paraxial region thereof and animage-side surface 562 being concave in a paraxial region thereof. Thesixth lens element 560 is made of plastic material and has theobject-side surface 561 and the image-side surface 562 being bothaspheric. The object-side surface 561 of the sixth lens element 560 hasat least one concave shape in an off-axis region thereof. The image-sidesurface 562 of the sixth lens element 560 has at least one convex shapein an off-axis region thereof.

The seventh lens element 570 with negative refractive power has anobject-side surface 571 being concave in a paraxial region thereof andan image-side surface 572 being concave in a paraxial region thereof.The seventh lens element 570 is made of plastic material and has theobject-side surface 571 and the image-side surface 572 being bothaspheric. The image-side surface 572 of the seventh lens element 570 hasat least one convex shape in an off-axis region thereof.

The IR-cut filter 580 is made of glass and located between the seventhlens element 570 and the image surface 590, and will not affect thefocal length of the photographing system. The image sensor 595 isdisposed on or near the image surface 590 of the photographing system.

The detailed optical data of the 5th embodiment are shown in Table 9 andthe aspheric surface data are shown in Table 10 below.

TABLE 9 5th Embodiment f = 4.93 mm, Fno = 2.45, HFOV = 37.5 deg. FocalSurface# Curvature Radius Thickness Material Index Abbe # Length 0Object Plano Infinity 1 Ape. Stop Plano −0.298 2 Lens 1 1.768 (ASP)0.659 Plastic 1.535 55.7 3.40 3 56.102 (ASP) 0.050 4 Lens 2 −41.070(ASP) 0.280 Plastic 1.639 23.5 −6.04 5 4.270 (ASP) 0.214 6 Lens 3 4.288(ASP) 0.312 Plastic 1.544 55.9 47.77 7 5.004 (ASP) 0.242 8 Lens 4 7.870(ASP) 0.284 Plastic 1.639 23.5 −60.45 9 6.446 (ASP) 0.299 10 Lens 5−11.573 (ASP) 0.408 Plastic 1.544 55.9 10.73 11 −3.928 (ASP) 0.403 12Lens 6 5.596 (ASP) 0.315 Plastic 1.583 30.2 19.18 13 10.962 (ASP) 0.68714 Lens 7 −46.920 (ASP) 0.398 Plastic 1.544 55.9 −4.02 15 2.304 (ASP)0.400 16 IR-cut filter Plano 0.300 Glass 1.517 64.2 — 17 Plano 0.249 18Image Plano — Note: Reference wavelength is 587.6 nm (d-line).

TABLE 10 Aspheric Coefficients Surface # 2 3 4 5 6 k =  3.9271E−02 4.0000E+01  9.0000E+01 −6.1044E−01 −9.4495E+00 A4 = −1.5959E−03−5.3428E−02 −2.9594E−02  1.3068E−02 −1.3379E−02 A6 = −3.3386E−03 6.9472E−02  7.1244E−02  2.2157E−02 −2.5819E−02 A8 = −1.0893E−03−5.9709E−02 −1.6422E−02  1.1943E−02 −2.6454E−02 A10 = −5.7545E−03 1.8689E−02 −2.2525E−02 −1.5604E−03  3.8215E−02 A12 =  6.4057E−03 6.4985E−04  2.1912E−02  1.2121E−02 −8.1341E−03 A14 = −6.5069E−03−6.7694E−03 −7.4544E−03 −5.0219E−03  2.6884E−03 Surface # 7 8 9 10 11 k= −1.8781E+01 −9.0000E+01 −2.9945E+01  6.9745E+01  2.5400E+00 A4 =−6.3922E−03 −1.0736E−01 −1.1365E−01  5.5378E−03  6.9241E−03 A6 =−1.6463E−02  2.8007E−02  1.5821E−02 −6.5774E−02 −4.5722E−02 A8 =−1.4360E−02 −1.8599E−03 −2.0513E−03  4.8435E−02  4.1810E−02 A10 = 1.4517E−03 −6.7075E−03 −8.9044E−03 −5.2428E−02 −2.9160E−02 A12 = 2.7419E−03 −4.3673E−04  1.1063E−02  2.3869E−02  9.1662E−03 A14 = — —−4.0069E−03 −2.9644E−03 −8.0345E−04 A16 = — —  5.7516E−04 — — Surface #12 13 14 15 k = −1.0252E+01  1.1420E+01 −1.0000E+00 −1.1263E+01 A4 =−8.3358E−03  3.0217E−02 −1.4433E−01 −7.8855E−02 A6 = −7.6866E−02−1.0210E−01  4.3140E−02  2.0785E−02 A8 =  1.6170E−02  4.7675E−02−3.9431E−03 −2.0176E−03 A10 =  8.0143E−03 −1.0924E−02 −5.0414E−04−3.1466E−04 A12 = −4.7939E−03  1.3539E−03  1.5731E−04  9.8165E−05 A14 = 6.6313E−04 −7.3421E−05 −1.4437E−05 −9.3356E−06 A16 = — —  4.7441E−07 3.1850E−07

In the 5th embodiment, the equation of the aspheric surface profiles ofthe aforementioned lens elements is the same as the equation of the 1stembodiment. Also, the definitions of these parameters shown in thefollowing table are the same as those stated in the 1st embodiment withcorresponding values for the 5th embodiment, so an explanation in thisregard will not be provided again.

Moreover, these parameters can be calculated from Table 9 and Table 10as the following values and satisfy the following conditions:

5th Embodiment f [mm] 4.93 ΣAT/(T34 + T45) 3.50 Fno 2.45 (f/R12) −(f/R13) 0.55 HFOV [deg.] 37.5 |f1/f2| 0.56 V2 23.5 |f/f3| + |f/f4| +|f/f5| 0.64 V1 − V2 32.20 f/f345 0.46 Dr1r8/Dr9r14 0.92

6th Embodiment

FIG. 11 is a schematic view of an image capturing unit according to the6th embodiment of the present disclosure. FIG. 12 shows, in order fromleft to right, spherical aberration curves, astigmatic field curves anda distortion curve of the image capturing unit according to the 6thembodiment. In FIG. 11, the image capturing unit includes thephotographing system (its reference numeral is omitted) of the presentdisclosure and an image sensor 695. The photographing system includes,in order from an object side to an image side, an aperture stop 600, afirst lens element 610, a second lens element 620, a third lens element630, a fourth lens element 640, a fifth lens element 650, a sixth lenselement 660, a seventh lens element 670, an IR-cut filter 680 and animage surface 690, wherein the photographing system has a total of sevenlens elements (610-670) with refractive power. The first lens element610, the second lens element 620, the third lens element 630, the fourthlens element 640, the fifth lens element 650, the sixth lens element 660and the seventh lens element 670 are all stationary relative to oneanother in a paraxial region thereof. There is an air gap in a paraxialregion between every two of the first lens element 610, the second lenselement 620, the third lens element 630, the fourth lens element 640,the fifth lens element 650, the sixth lens element 660 and the seventhlens element 670 that are adjacent to each other.

The first lens element 610 with positive refractive power has anobject-side surface 611 being convex in a paraxial region thereof and animage-side surface 612 being concave in a paraxial region thereof. Thefirst lens element 610 is made of plastic material and has theobject-side surface 611 and the image-side surface 612 being bothaspheric.

The second lens element 620 with negative refractive power has anobject-side surface 621 being convex in a paraxial region thereof and animage-side surface 622 being concave in a paraxial region thereof. Thesecond lens element 620 is made of plastic material and has theobject-side surface 621 and the image-side surface 622 being bothaspheric.

The third lens element 630 with positive refractive power has anobject-side surface 631 being convex in a paraxial region thereof and animage-side surface 632 being convex in a paraxial region thereof. Thethird lens element 630 is made of plastic material and has theobject-side surface 631 and the image-side surface 632 being bothaspheric.

The fourth lens element 640 with negative refractive power has anobject-side surface 641 being concave in a paraxial region thereof andan image-side surface 642 being convex in a paraxial region thereof. Thefourth lens element 640 is made of plastic material and has theobject-side surface 641 and the image-side surface 642 being bothaspheric.

The fifth lens element 650 with negative refractive power has anobject-side surface 651 being concave in a paraxial region thereof andan image-side surface 652 being convex in a paraxial region thereof. Thefifth lens element 650 is made of plastic material and has theobject-side surface 651 and the image-side surface 652 being bothaspheric.

The sixth lens element 660 with positive refractive power has anobject-side surface 661 being convex in a paraxial region thereof and animage-side surface 662 being concave in a paraxial region thereof. Thesixth lens element 660 is made of plastic material and has theobject-side surface 661 and the image-side surface 662 being bothaspheric. The object-side surface 661 of the sixth lens element 660 hasat least one concave shape in an off-axis region thereof. The image-sidesurface 662 of the sixth lens element 660 has at least one convex shapein an off-axis region thereof.

The seventh lens element 670 with negative refractive power has anobject-side surface 671 being concave in a paraxial region thereof andan image-side surface 672 being concave in a paraxial region thereof.The seventh lens element 670 is made of plastic material and has theobject-side surface 671 and the image-side surface 672 being bothaspheric. The image-side surface 672 of the seventh lens element 670 hasat least one convex shape in an off-axis region thereof.

The IR-cut filter 680 is made of glass and located between the seventhlens element 670 and the image surface 690, and will not affect thefocal length of the photographing system. The image sensor 695 isdisposed on or near the image surface 690 of the photographing system.

The detailed optical data of the 6th embodiment are shown in Table 11and the aspheric surface data are shown in Table 12 below.

TABLE 11 6th Embodiment f = 3.80 mm, Fno = 1.98, HFOV = 37.5 deg. FocalSurface# Curvature Radius Thickness Material Index Abbe # Length 0Object Plano Infinity 1 Ape. Stop Plano −0.318 2 Lens 1 1.660 (ASP)0.537 Plastic 1.544 55.9 3.47 3 12.273 (ASP) 0.092 4 Lens 2 3.330 (ASP)0.245 Plastic 1.639 23.5 −6.69 5 1.818 (ASP) 0.366 6 Lens 3 8.541 (ASP)0.528 Plastic 1.535 55.7 5.22 7 −4.055 (ASP) 0.060 8 Lens 4 −3.918 (ASP)0.230 Plastic 1.614 25.6 −126.54 9 −4.218 (ASP) 0.175 10 Lens 5 −1.225(ASP) 0.300 Plastic 1.614 25.6 −6.84 11 −1.890 (ASP) 0.050 12 Lens 62.097 (ASP) 0.675 Plastic 1.544 55.9 4.54 13 12.313 (ASP) 0.580 14 Lens7 −3.059 (ASP) 0.292 Plastic 1.535 55.7 −3.23 15 4.104 (ASP) 0.310 16IR-cut filter Plano 0.200 Glass 1.517 64.2 — 17 Plano 0.142 18 ImagePlano — Note: Reference wavelength is 587.6 nm (d-line). Effectiveradius of surface 11 is 1.400 mm.

TABLE 12 Aspheric Coefficients Surface # 2 3 4 5 6 k = −2.3265E−021.0000E+01 −2.5499E+01 −4.8861E+00 −1.0000E+00 A4 =  6.3659E−03−8.0057E−02  −1.3467E−01 −6.0233E−02 −6.4068E−02 A6 =  1.9529E−022.1444E−01  2.8774E−01  1.9541E−01  4.5669E−03 A8 = −2.7679E−02−2.8820E−01  −3.9527E−01 −1.7958E−01 −5.5809E−02 A10 =  3.6299E−022.1958E−01  3.9961E−01  7.5264E−02  5.2159E−02 A12 = −1.3490E−02−4.0489E−02  −3.2083E−01  9.5720E−02 −3.1446E−02 A14 =  2.9287E−03−4.9456E−02   1.7339E−01 −1.4441E−01  1.9873E−02 A16 = −9.0555E−041.4853E−02 −6.1122E−02  5.9649E−02  2.9564E−03 Surface # 7 8 9 10 11 k = 8.8598E+00 9.8492E+00  5.3732E+00 −6.3648E+00 −8.2947E−01 A4 =−5.4576E−02 −6.6158E−02  −5.7893E−02  1.5653E−02  8.4047E−02 A6 =−2.6424E−02 1.9517E−02  5.5584E−02  4.7473E−03 −1.1716E−02 A8 = 7.0055E−03 8.0045E−03 −1.5171E−01  1.1483E−03  1.8725E−02 A10 = 1.3962E−02 3.5053E−03  2.3797E−01 −2.8584E−03 −5.4917E−03 A12 = 4.0109E−03 4.6121E−03 −2.3131E−01  1.8727E−03 −6.6369E−04 A14 =−1.9337E−03 2.2693E−03  1.2464E−01  1.0961E−03  2.6290E−04 A16 =−1.5487E−03 −2.8316E−03  −2.7289E−02 −9.6837E−04 — Surface # 12 13 14 15k = −1.9457E+01 9.3259E+00  5.2106E−01 −7.4915E+00 A4 = −1.7518E−022.1927E−02 −3.1905E−02 −6.6764E−02 A6 = −3.6621E−02 −6.7859E−02 −6.3825E−02 −3.7548E−03 A8 =  1.5738E−02 4.3398E−02  5.6545E−02 1.0680E−02 A10 =  4.3524E−04 −1.7567E−02  −1.5869E−02 −4.1816E−03 A12 =−7.1276E−03 4.1763E−03  1.4618E−03  8.4984E−04 A14 =  3.1671E−03−5.2169E−04   7.9648E−05 −9.3204E−05 A16 = −3.7171E−04 2.5522E−05−1.5105E−05  4.2174E−06

In the 6th embodiment, the equation of the aspheric surface profiles ofthe aforementioned lens elements is the same as the equation of the 1stembodiment. Also, the definitions of these parameters shown in thefollowing table are the same as those stated in the 1st embodiment withcorresponding values for the 6th embodiment, so an explanation in thisregard will not be provided again.

Moreover, these parameters can be calculated from Table 11 and Table 12as the following values and satisfy the following conditions:

6th Embodiment f [mm] 3.80 ΣAT/(T34 + T45) 5.63 Fno 1.98 (f/R12) −(f/R13) 1.55 HFOV [deg.] 37.5 |f1/f2| 0.52 V2 23.5 |f/f3| + |f/f4| +|f/f5| 1.31 V1 − V2 32.40 f/f345 0.13 Dr1r8/Dr9r14 1.08

7th Embodiment

FIG. 13 is a schematic view of an image capturing unit according to the7th embodiment of the present disclosure. FIG. 14 shows, in order fromleft to right, spherical aberration curves, astigmatic field curves anda distortion curve of the image capturing unit according to the 7thembodiment. In FIG. 13, the image capturing unit includes thephotographing system (its reference numeral is omitted) of the presentdisclosure and an image sensor 795. The photographing system includes,in order from an object side to an image side, a first lens element 710,an aperture stop 700, a second lens element 720, a third lens element730, a fourth lens element 740, a fifth lens element 750, a sixth lenselement 760, a seventh lens element 770, an IR-cut filter 780 and animage surface 790, wherein the photographing system has a total of sevenlens elements (710-770) with refractive power. The first lens element710, the second lens element 720, the third lens element 730, the fourthlens element 740, the fifth lens element 750, the sixth lens element 760and the seventh lens element 770 are all stationary relative to oneanother in a paraxial region thereof. There is an air gap in a paraxialregion between every two of the first lens element 710, the second lenselement 720, the third lens element 730, the fourth lens element 740,the fifth lens element 750, the sixth lens element 760 and the seventhlens element 770 that are adjacent to each other.

The first lens element 710 with positive refractive power has anobject-side surface 711 being convex in a paraxial region thereof and animage-side surface 712 being concave in a paraxial region thereof. Thefirst lens element 710 is made of plastic material and has theobject-side surface 711 and the image-side surface 712 being bothaspheric.

The second lens element 720 with positive refractive power has anobject-side surface 721 being convex in a paraxial region thereof and animage-side surface 722 being concave in a paraxial region thereof. Thesecond lens element 720 is made of plastic material and has theobject-side surface 721 and the image-side surface 722 being bothaspheric.

The third lens element 730 with positive refractive power has anobject-side surface 731 being convex in a paraxial region thereof and animage-side surface 732 being convex in a paraxial region thereof. Thethird lens element 730 is made of plastic material and has theobject-side surface 731 and the image-side surface 732 being bothaspheric.

The fourth lens element 740 with negative refractive power has anobject-side surface 741 being concave in a paraxial region thereof andan image-side surface 742 being convex in a paraxial region thereof. Thefourth lens element 740 is made of plastic material and has theobject-side surface 741 and the image-side surface 742 being bothaspheric.

The fifth lens element 750 with negative refractive power has anobject-side surface 751 being concave in a paraxial region thereof andan image-side surface 752 being convex in a paraxial region thereof. Thefifth lens element 750 is made of plastic material and has theobject-side surface 751 and the image-side surface 752 being bothaspheric.

The sixth lens element 760 with positive refractive power has anobject-side surface 761 being convex in a paraxial region thereof and animage-side surface 762 being concave in a paraxial region thereof. Thesixth lens element 760 is made of plastic material and has theobject-side surface 761 and the image-side surface 762 being bothaspheric. The object-side surface 761 of the sixth lens element 760 hasat least one concave shape in an off-axis region thereof. The image-sidesurface 762 of the sixth lens element 760 has at least one convex shapein an off-axis region thereof.

The seventh lens element 770 with negative refractive power has anobject-side surface 771 being concave in a paraxial region thereof andan image-side surface 772 being concave in a paraxial region thereof.The seventh lens element 770 is made of plastic material and has theobject-side surface 771 and the image-side surface 772 being bothaspheric. The image-side surface 772 of the seventh lens element 770 hasat least one convex shape in an off-axis region thereof.

The IR-cut filter 780 is made of glass and located between the seventhlens element 770 and the image surface 790, and will not affect thefocal length of the photographing system. The image sensor 795 isdisposed on or near the image surface 790 of the photographing system.

The detailed optical data of the 7th embodiment are shown in Table 13and the aspheric surface data are shown in Table 14 below.

TABLE 13 7th Embodiment f = 3.51 mm, Fno = 2.07, HFOV = 39.4 deg. FocalSurface# Curvature Radius Thickness Material Index Abbe # Length 0Object Plano Infinity 1 Lens 1 2.201 (ASP) 0.470 Plastic 1.544 55.9 6.402 5.534 (ASP) 0.077 3 Ape. Stop Plano −0.017 4 Lens 2 2.312 (ASP) 0.341Plastic 1.544 55.9 31.87 5 2.529 (ASP) 0.229 6 Lens 3 15.572 (ASP) 0.501Plastic 1.544 55.9 3.73 7 −2.308 (ASP) 0.050 8 Lens 4 −1.991 (ASP) 0.425Plastic 1.639 23.5 −13.78 9 −2.787 (ASP) 0.069 10 Lens 5 −1.120 (ASP)0.300 Plastic 1.639 23.5 −4.63 11 −1.992 (ASP) 0.050 12 Lens 6 1.794(ASP) 0.720 Plastic 1.544 55.9 3.34 13 121.752 (ASP) 0.580 14 Lens 7−8.838 (ASP) 0.400 Plastic 1.544 55.9 −2.95 15 1.989 (ASP) 0.310 16IR-cut filter Plano 0.200 Glass 1.517 64.2 — 17 Plano 0.195 18 ImagePlano — Note: Reference wavelength is 587.6 nm (d-line).

TABLE 14 Aspheric Coefficients Surface # 1 2 4 5 6 k = 2.6138E−01−2.0537E+01  −4.7803E+00 −4.7705E+00 −1.0000E+00 A4 = 8.1081E−03−8.1050E−02  −1.5997E−01 −1.3501E−01 −1.2599E−01 A6 = 3.0050E−023.3025E−01  3.4966E−01 −8.8107E−02 −1.0028E−01 A8 = −3.5734E−02 −3.5845E−01  −6.2036E−01  8.5801E−02 −7.4847E−02 A10 = 7.6055E−022.4175E−01  8.4893E−01 −3.8375E−01 −3.6298E−02 A12 = −1.7011E−02 3.5173E−02 −9.2063E−01  3.6112E−01 −7.3642E−02 A14 = −4.9322E−02 −4.7817E−02   5.8447E−01 −1.9399E−01  7.0546E−02 A16 = 4.2690E−025.5762E−02 −1.9510E−01  5.5798E−02  1.1109E−01 Surface # 7 8 9 10 11 k =2.3826E+00 2.1967E+00  1.0000E−01 −5.7792E+00 −1.7394E+00 A4 =−2.1867E−01  −2.3898E−01  −5.6902E−02  1.2840E−01  1.0842E−01 A6 =−9.0637E−03  3.9903E−02  7.8166E−02  9.9593E−03  8.3228E−03 A8 =1.3529E−02 8.3262E−02 −1.4459E−01 −1.1907E−02  1.1317E−02 A10 =5.3081E−02 2.8975E−02  2.4076E−01 −1.0814E−02 −9.8670E−03 A12 =2.2363E−02 2.3308E−02 −2.3324E−01  2.4497E−03 −1.2972E−03 A14 =−1.6846E−02  1.8296E−02  1.2205E−01  3.7424E−03  8.2692E−04 A16 =1.1981E−03 −2.1303E−02  −2.4198E−02 −1.8079E−03 — Surface # 12 13 14 15k = −1.4625E+01  1.0000E+01  9.9847E+00 −3.0381E+00 A4 = 1.1432E−021.0655E−01 −8.1518E−02 −1.1986E−01 A6 = −4.3054E−02  −1.4661E−01 −3.5435E−02  4.5316E−02 A8 = 1.8657E−02 1.0308E−01  1.5124E−02−1.5720E−02 A10 = 1.3287E−03 −4.6724E−02   1.4995E−02  4.0575E−03 A12 =−9.1760E−03  1.2782E−02 −1.0281E−02 −7.1080E−04 A14 = 4.5440E−03−1.9542E−03   2.3332E−03  7.5489E−05 A16 = −7.7703E−04  1.2654E−04−1.8882E−04 −3.5905E−06

In the 7th embodiment, the equation of the aspheric surface profiles ofthe aforementioned lens elements is the same as the equation of the 1stembodiment. Also, the definitions of these parameters shown in thefollowing table are the same as those stated in the 1st embodiment withcorresponding values for the 7th embodiment, so an explanation in thisregard will not be provided again.

Moreover, these parameters can be calculated from Table 13 and Table 14as the following values and satisfy the following conditions:

7th Embodiment f [mm] 3.51 ΣAT/(T34 + T45) 8.72 Fno 2.07 (f/R12) −(f/R13) 0.43 HFOV [deg.] 39.4 |f1/f2| 0.20 V2 55.9 |f/f3| + |f/f4| +|f/f5| 1.95 V1 − V2 0.00 f/f345 −0.14 Dr1r8/Dr9r14 1.01

8th Embodiment

FIG. 15 is a schematic view of an image capturing unit according to the8th embodiment of the present disclosure. FIG. 16 shows, in order fromleft to right, spherical aberration curves, astigmatic field curves anda distortion curve of the image capturing unit according to the 8thembodiment. In FIG. 15, the image capturing unit includes thephotographing system (its reference numeral is omitted) of the presentdisclosure and an image sensor 895. The photographing system includes,in order from an object side to an image side, an aperture stop 800, afirst lens element 810, a second lens element 820, a third lens element830, a fourth lens element 840, a fifth lens element 850, a sixth lenselement 860, a seventh lens element 870, an IR-cut filter 880 and animage surface 890, wherein the photographing system has a total of sevenlens elements (810-870) with refractive power. The first lens element810, the second lens element 820, the third lens element 830, the fourthlens element 840, the fifth lens element 850, the sixth lens element 860and the seventh lens element 870 are all stationary relative to oneanother in a paraxial region thereof. There is an air gap in a paraxialregion between every two of the first lens element 810, the second lenselement 820, the third lens element 830, the fourth lens element 840,the fifth lens element 850, the sixth lens element 860 and the seventhlens element 870 that are adjacent to each other.

The first lens element 810 with positive refractive power has anobject-side surface 811 being convex in a paraxial region thereof and animage-side surface 812 being concave in a paraxial region thereof. Thefirst lens element 810 is made of plastic material and has theobject-side surface 811 and the image-side surface 812 being bothaspheric.

The second lens element 820 with negative refractive power has anobject-side surface 821 being convex in a paraxial region thereof and animage-side surface 822 being concave in a paraxial region thereof. Thesecond lens element 820 is made of plastic material and has theobject-side surface 821 and the image-side surface 822 being bothaspheric.

The third lens element 830 with positive refractive power has anobject-side surface 831 being convex in a paraxial region thereof and animage-side surface 832 being convex in a paraxial region thereof. Thethird lens element 830 is made of plastic material and has theobject-side surface 831 and the image-side surface 832 being bothaspheric.

The fourth lens element 840 with negative refractive power has anobject-side surface 841 being concave in a paraxial region thereof andan image-side surface 842 being concave in a paraxial region thereof.The fourth lens element 840 is made of plastic material and has theobject-side surface 841 and the image-side surface 842 being bothaspheric.

The fifth lens element 850 with positive refractive power has anobject-side surface 851 being concave in a paraxial region thereof andan image-side surface 852 being convex in a paraxial region thereof. Thefifth lens element 850 is made of plastic material and has theobject-side surface 851 and the image-side surface 852 being bothaspheric.

The sixth lens element 860 with positive refractive power has anobject-side surface 861 being convex in a paraxial region thereof and animage-side surface 862 being concave in a paraxial region thereof. Thesixth lens element 860 is made of plastic material and has theobject-side surface 861 and the image-side surface 862 being bothaspheric. The object-side surface 861 of the sixth lens element 860 hasat least one concave shape in an off-axis region thereof. The image-sidesurface 862 of the sixth lens element 860 has at least one convex shapein an off-axis region thereof.

The seventh lens element 870 with negative refractive power has anobject-side surface 871 being concave in a paraxial region thereof andan image-side surface 872 being concave in a paraxial region thereof.The seventh lens element 870 is made of plastic material and has theobject-side surface 871 and the image-side surface 872 being bothaspheric. The image-side surface 872 of the seventh lens element 870 hasat least one convex shape in an off-axis region thereof.

The IR-cut filter 880 is made of glass and located between the seventhlens element 870 and the image surface 890, and will not affect thefocal length of the photographing system. The image sensor 895 isdisposed on or near the image surface 890 of the photographing system.

The detailed optical data of the 8th embodiment are shown in Table 15and the aspheric surface data are shown in Table 16 below.

TABLE 15 8th Embodiment f = 4.33 mm, Fno = 2.03, HFOV = 38.4 deg. FocalSurface# Curvature Radius Thickness Material Index Abbe # Length 0Object Plano Infinity 1 Ape. Stop Plano −0.357 2 Lens 1 1.856 (ASP)0.546 Plastic 1.560 56.0 3.86 3 11.633 (ASP) 0.112 4 Lens 2 4.450 (ASP)0.245 Plastic 1.660 21.0 −7.58 5 2.303 (ASP) 0.419 6 Lens 3 8.749 (ASP)0.542 Plastic 1.560 56.0 15.33 7 −444.319 (ASP) 0.143 8 Lens 4 −46.895(ASP) 0.250 Plastic 1.600 32.0 −21.40 9 17.713 (ASP) 0.181 10 Lens 5−2.257 (ASP) 0.318 Plastic 1.560 56.0 19.53 11 −1.966 (ASP) 0.050 12Lens 6 2.738 (ASP) 0.561 Plastic 1.560 56.0 6.16 13 12.313 (ASP) 0.70014 Lens 7 −6.361 (ASP) 0.292 Plastic 1.560 56.0 −3.69 15 3.115 (ASP)0.310 16 IR-cut filter Plano 0.300 Glass 1.517 64.2 — 17 Plano 0.368 18Image Plano — Note: Reference wavelength is 587.6 nm (d-line).

TABLE 16 Aspheric Coefficients Surface # 2 3 4 5 6 k = −2.1880E−02−3.0000E+01 −1.9542E+01 −4.4496E+00 −1.0000E+00 A4 =  5.5012E−03−4.2990E−02 −1.0428E−01 −5.0033E−02 −4.6326E−02 A6 =  9.3604E−03 1.2625E−01  2.4979E−01  1.6305E−01 −1.6375E−02 A8 = −1.4197E−02−1.6433E−01 −4.1241E−01 −2.0224E−01 −4.3482E−03 A10 =  2.0744E−02 1.1033E−01  5.5494E−01  2.2551E−01  1.7310E−02 A12 =  8.6700E−04 3.1130E−02 −5.1950E−01 −1.8057E−01 −1.9138E−02 A14 = −1.4709E−02−8.9067E−02  2.7578E−01  8.5000E−02 −7.9946E−03 A16 =  7.8947E−03 3.6512E−02 −6.3529E−02 −1.5636E−02  9.7877E−03 Surface # 7 8 9 10 11 k= −3.0000E+01 −3.0000E+01 −3.0000E+01 −1.7654E+01 −3.6147E−01 A4 =−7.1744E−02 −1.6177E−01 −1.1249E−01  1.7471E−02 −6.1712E−03 A6 =−4.2104E−02  8.6448E−03  3.1544E−02 −2.7356E−02  1.2858E−02 A8 = 3.6360E−03  5.7906E−03 −4.1788E−02  3.4043E−04  9.4765E−03 A10 =−6.4873E−03  8.0492E−03  5.8318E−02  1.7761E−03 −1.2794E−03 A12 = 3.2991E−03  2.8954E−03 −4.1849E−02  1.2167E−03 −2.7139E−04 A14 = 3.8455E−03 −5.9588E−05  1.5951E−02  2.3355E−04 −1.8358E−05 A16 =−2.0694E−03 −1.1695E−03 −2.3502E−03 −1.9500E−04 — Surface # 12 13 14 15k = −3.0000E+01  4.5984E−01 −2.6869E+01 −6.5262E+00 A4 = −3.0609E−02−3.1322E−02 −1.8801E−01 −1.4199E−01 A6 = −7.3723E−02 −5.5240E−02 3.5183E−02  4.9946E−02 A8 =  8.1443E−02  4.1654E−02 −3.6592E−03−1.3885E−02 A10 = −5.1968E−02 −1.8208E−02 −1.3605E−04  2.5644E−03 A12 = 2.1245E−02  5.0383E−03  6.6904E−04 −2.4963E−04 A14 = −5.3090E−03−7.9598E−04 −1.6512E−04  5.3178E−06 A16 =  5.8123E−04  5.4859E−05 1.1125E−05  5.1910E−07

In the 8th embodiment, the equation of the aspheric surface profiles ofthe aforementioned lens elements is the same as the equation of the 1stembodiment. Also, the definitions of these parameters shown in thefollowing table are the same as those stated in the 1st embodiment withcorresponding values for the 8th embodiment, so an explanation in thisregard will not be provided again.

Moreover, these parameters can be calculated from Table 15 and Table 16as the following values and satisfy the following conditions:

8th Embodiment f [mm] 4.33 ΣAT/(T34 + T45) 4.95 Fno 2.03 (f/R12) −(f/R13) 1.03 HFOV [deg.] 38.4 |f1/f2| 0.51 V2 21.0 |f/f3| + |f/f4| +|f/f5| 0.71 V1 − V2 35.20 f/f345 0.27 Dr1r8/Dr9r14 1.17

The foregoing image capturing unit is able to be installed in, but notlimited to, an electronic device. According to the present disclosure,the photographing system has a total of seven lens elements withrefractive power. The image-side surface of the sixth lens element isconcave in a paraxial region thereof, and the object-side surface of theseventh lens element is concave in a paraxial region thereof. Therefore,it is favorable for the exit pupil of the photographing system beingpositioned towards the image surface of the photographing system so asto effectively reduce the back focal length of the photographing system,thereby keeping a compact size thereof. When specific conditions aresatisfied, it is favorable for allocating the curvatures of the sixthlens element and the seventh lens element so as to reduce thesensitivity of the photographing system and increase the manufacturingyield rate. According to the present disclosure, the photographingsystem is favorable for satisfying the requirements of high imagequality and compact size simultaneously.

The foregoing description, for the purpose of explanation, has beendescribed with reference to specific embodiments. It is to be noted thatTABLES 1-16 show different data of the different embodiments; however,the data of the different embodiments are obtained from experiments. Theembodiments were chosen and described in order to best explain theprinciples of the disclosure and its practical applications, to therebyenable others skilled in the art to best utilize the disclosure andvarious embodiments with various modifications as are suited to theparticular use contemplated. The embodiments depicted above and theappended drawings are exemplary and are not intended to be exhaustive orto limit the scope of the present disclosure to the precise formsdisclosed. Many modifications and variations are possible in view of theabove teachings.

What is claimed is:
 1. A photographing system comprising seven lenselements, the seven lens elements being, in order from an object side toan image side: a first lens element with positive refractive powerhaving an object-side surface being convex in a paraxial region thereof;a second lens element having an image-side surface being concave in aparaxial region thereof; a third lens element having an object-sidesurface being convex in a paraxial region thereof; a fourth lens elementhaving an object-side surface being convex in a paraxial region thereof;a fifth lens element; a sixth lens element having an image-side surfacebeing concave in a paraxial region thereof, wherein the image-sidesurface of the sixth lens element has at least one convex critical pointin an off-axis region thereof, and an object-side surface and theimage-side surface of the sixth lens element are both aspheric; and aseventh lens element; wherein there is an air gap in a paraxial regionbetween every two of the first lens element, the second lens element,the third lens element, the fourth lens element, the fifth lens element,the sixth lens element and the seventh lens element that are adjacent toeach other, and an axial distance between the sixth lens element and theseventh lens element is a maximum among axial distances beingrespectively between every two lens elements of the first lens element,the second lens element, the third lens element, the fourth lenselement, the fifth lens element, the sixth lens element and the seventhlens element that are adjacent to each other.
 2. The photographingsystem of claim 1, wherein the second lens element has an object-sidesurface being convex in a paraxial region thereof.
 3. The photographingsystem of claim 1, wherein the fifth lens element has an object-sidesurface being concave in a paraxial region thereof and an image-sidesurface being convex in a paraxial region thereof.
 4. The photographingsystem of claim 1, wherein the seventh lens element with negativerefractive power has an object-side surface being concave in a paraxialregion thereof, and the object-side surface of the seventh lens elementhas at least one convex shape in an off-axis region thereof.
 5. Thephotographing system of claim 1, wherein the first lens element has animage-side surface being concave in a paraxial region thereof.
 6. Thephotographing system of claim 1, wherein the second lens element hasnegative refractive power, an Abbe number of the first lens element isV1, an Abbe number of the second lens element is V2, and the followingcondition is satisfied:25<V1−V2<45.
 7. The photographing system of claim 1, wherein a focallength of the photographing system is f, a composite focal length of thethird lens element, the fourth lens element and the fifth lens elementis f345, and the following condition is satisfied:−0.30<f/f345<0.60.
 8. The photographing system of claim 1, wherein theobject-side surface of the sixth lens element is convex in a paraxialregion thereof, and the object-side surface of the sixth lens elementhas at least one concave shape in an off-axis region thereof.
 9. Thephotographing system of claim 1, wherein a sum of the axial distancesbeing respectively between every two lens elements of the first lenselement, the second lens element, the third lens element, the fourthlens element, the fifth lens element, the sixth lens element and theseventh lens element that are adjacent to each other is ΣAT, an axialdistance between the third lens element and the fourth lens element isT34, an axial distance between the fourth lens element and the fifthlens element is T45, and the following condition is satisfied:3.0<ΣAT/(T34+T45)<10.0.
 10. The photographing system of claim 1, whereina focal length of the photographing system is f, a curvature radius ofthe image-side surface of the sixth lens element is R12, a curvatureradius of an object-side surface of the seventh lens element is R13, andthe following condition is satisfied:0.30<(f/R12)−(f/R13).
 11. The photographing system of claim 10, whereinthe focal length of the photographing system is f, the curvature radiusof the image-side surface of the sixth lens element is R12, thecurvature radius of the object-side surface of the seventh lens elementis R13, and the following condition is satisfied:0.40<(f/R12)−(f/R13)<3.5.
 12. The photographing system of claim 1,wherein a focal length of the photographing system is f, a focal lengthof the third lens element is f3, a focal length of the fourth lenselement is f4, a focal length of the fifth lens element is f5, and thefollowing condition is satisfied:|f/f3|+|f/f4|+|f/f5|<1.5.
 13. The photographing system of claim 1,wherein an axial distance between the object-side surface of the firstlens element and an image-side surface of the fourth lens element isDr1r8, an axial distance between an object-side surface of the fifthlens element and an image-side surface of the seventh lens element isDr9r14, and the following condition is satisfied:0.75<Dr1r8/Dr9r14<1.5.
 14. The photographing system of claim 1, whereina focal length of the first lens element is f1, a focal length of thesecond lens element is f2, an f-number of the photographing system isFno, and the following conditions are satisfied:|f1/f2|<0.80; andFno≦2.25.
 15. The photographing system of claim 1, wherein a focallength of the first lens element is f1, a focal length of the secondlens element is f2, a focal length of the third lens element is f3, afocal length of the fourth lens element is f4, a focal length of thefifth lens element is f5, a focal length of the sixth lens element isf6, a focal length of the seventh lens element is f7, a focal length ofthe x-th lens element is fx, and the following conditions are satisfied:|f1|<|fx|; and|f7|<|fx|, wherein x=2,3,4,5,6.
 16. The photographing system of claim 1,wherein the seventh lens element has an image-side surface being concavein a paraxial region thereof, and a projection of a position of amaximum effective radius of the image-side surface of the seventh lenselement on an optical axis is closer to the object side of thephotographing system than an intersection of an object-side surface ofthe seventh lens element and the optical axis.
 17. An image capturingunit, comprising: the photographing system of claim 1; and an imagesensor disposed on the image side of the photographing system.
 18. Anelectronic device, comprising: the image capturing unit of claim
 17. 19.A photographing system comprising seven lens elements, the seven lenselements being, in order from an object side to an image side: a firstlens element with positive refractive power having an object-sidesurface being convex in a paraxial region thereof; a second lens elementhaving an image-side surface being concave in a paraxial region thereof;a third lens element having an image-side surface being concave in aparaxial region thereof; a fourth lens element having an image-sidesurface being concave in a paraxial region thereof; a fifth lenselement; a sixth lens element having an image-side surface being concavein a paraxial region thereof, wherein the image-side surface of thesixth lens element has at least one convex critical point in an off-axisregion thereof, and an object-side surface and the image-side surface ofthe sixth lens element are both aspheric; and a seventh lens element;wherein there is an air gap in a paraxial region between every two ofthe first lens element, the second lens element, the third lens element,the fourth lens element, the fifth lens element, the sixth lens elementand the seventh lens element that are adjacent to each other, and anaxial distance between the sixth lens element and the seventh lenselement is a maximum among axial distances being respectively betweenevery two lens elements of the first lens element, the second lenselement, the third lens element, the fourth lens element, the fifth lenselement, the sixth lens element and the seventh lens element that areadjacent to each other.
 20. The photographing system of claim 19,wherein a sum of the axial distances being respectively between everytwo lens elements of the first lens element, the second lens element,the third lens element, the fourth lens element, the fifth lens element,the sixth lens element and the seventh lens element that are adjacent toeach other is ΣAT, an axial distance between the third lens element andthe fourth lens element is T34, an axial distance between the fourthlens element and the fifth lens element is T45, and the followingcondition is satisfied:3.0<ΣAT/(T34+T45)<10.0.
 21. The photographing system of claim 19,wherein a focal length of the photographing system is f, a focal lengthof the third lens element is f3, a focal length of the fourth lenselement is f4, a focal length of the fifth lens element is f5, and thefollowing condition is satisfied:|f/f3|+|f/f4|+|f/f5|<1.5.
 22. The photographing system of claim 19,wherein an axial distance between the object-side surface of the firstlens element and the image-side surface of the fourth lens element isDr1r8, an axial distance between an object-side surface of the fifthlens element and an image-side surface of the seventh lens element isDr9r14, and the following condition is satisfied:0.75<Dr1r8/Dr9r14<1.5.
 23. The photographing system of claim 19, whereina focal length of the photographing system is f, a composite focallength of the third lens element, the fourth lens element and the fifthlens element is f345, and the following condition is satisfied:−0.30<f/f345<0.60.
 24. The photographing system of claim 19, whereineach of the first lens element, the second lens element, the third lenselement, the fourth lens element, the fifth lens element and the sixthlens element is meniscus in a paraxial region thereof.
 25. Thephotographing system of claim 19, wherein the seventh lens element withnegative refractive power has an object-side surface being concave in aparaxial region thereof, and the object-side surface of the seventh lenselement has at least one convex shape in an off-axis region thereof. 26.The photographing system of claim 19, wherein a focal length of thefirst lens element is f1, a focal length of the second lens element isf2, a focal length of the third lens element is f3, a focal length ofthe fourth lens element is f4, a focal length of the fifth lens elementis f5, a focal length of the sixth lens element is f6, a focal length ofthe seventh lens element is f7, a focal length of the x-th lens elementis fx, and the following conditions are satisfied:|f1|<|fx|; and|f7|<|fx|, wherein x=2,3,4,5,6.
 27. The photographing system of claim19, wherein the seventh lens element has an image-side surface beingconcave in a paraxial region thereof, and a projection of a position ofa maximum effective radius of the image-side surface of the seventh lenselement on an optical axis is closer to the object side of thephotographing system than an intersection of an object-side surface ofthe seventh lens element and the optical axis.
 28. An image capturingunit, comprising: the photographing system of claim 19; and an imagesensor disposed on the image side of the photographing system.
 29. Anelectronic device, comprising: the image capturing unit of claim 28.